GitHub - szyhf/go-gcache: The Generic version of gcache. It supports multiple eviction policies: LRU, LFU, ARC. (original) (raw)

GCache

Test PkgGoDev

Cache library for golang. It supports expirable Cache, LFU, LRU and ARC.

It's the generic version of bluele/gcache.

Features

Install

$ go get github.com/szyhf/go-gcache/v2

Example

Manually set a key-value pair.

package main

import ( "fmt"

"github.com/szyhf/go-gcache/v2"

)

func main() { gc := gcache.Newstring, string. LRU(). Build() gc.Set("key", "ok") value, err := gc.Get("key") if err != nil { panic(err) } fmt.Println("Get:", value) }

Manually set a key-value pair, with an expiration time.

package main

import ( "fmt" "time"

"github.com/szyhf/go-gcache/v2"

)

func main() { gc := gcache.Newstring, string. LRU(). Build() gc.SetWithExpire("key", "ok", time.Second*10) value, _ := gc.Get("key") fmt.Println("Get:", value)

// Wait for value to expire
time.Sleep(time.Second * 10)

value, err := gc.Get("key")
if err != nil {
    panic(err)
}
fmt.Println("Get:", value)

}

Get: ok
// 10 seconds later, new attempt:
panic: ErrKeyNotFound

Automatically load value

package main

import ( "fmt"

gcache "github.com/szyhf/go-gcache/v2"

)

func main() { gc := gcache.Newstring, string. LRU(). LoaderFunc(func(key string) (string, error) { return "ok", nil }). Build() value, err := gc.Get("key") if err != nil { panic(err) } fmt.Println("Get:", value) }

Automatically load value with expiration

package main

import ( "fmt" "time"

"github.com/szyhf/go-gcache/v2" )

func main() { var evictCounter, loaderCounter, purgeCounter int gc := gcache.New(20). LRU(). LoaderExpireFunc(func(key any) (any, *time.Duration, error) { loaderCounter++ expire := 1 * time.Second return "ok", &expire, nil }). EvictedFunc(func(key, value any) { evictCounter++ fmt.Println("evicted key:", key) }). PurgeVisitorFunc(func(key, value any) { purgeCounter++ fmt.Println("purged key:", key) }). Build() value, err := gc.Get("key") if err != nil { panic(err) } fmt.Println("Get:", value) time.Sleep(1 * time.Second) value, err = gc.Get("key") if err != nil { panic(err) } fmt.Println("Get:", value) gc.Purge() if loaderCounter != evictCounter+purgeCounter { panic("bad") } }

Get: ok
evicted key: key
Get: ok
purged key: key

Cache Algorithm

Discards the least frequently used items first.

func main() { // size: 10 gc := gcache.Newstring, string. LFU(). Build() gc.Set("key", "value") }

Discards the least recently used items first.

func main() { // size: 10 gc := gcache.Newstring, string. LRU(). Build() gc.Set("key", "value") }

Constantly balances between LRU and LFU, to improve the combined result.

detail: http://en.wikipedia.org/wiki/Adaptive_replacement_cache

func main() { // size: 10 gc := gcache.Newstring, string. ARC(). Build() gc.Set("key", "value") }

SimpleCache has no clear priority for evict cache. It depends on key-value map order.

func main() { // size: 10 gc := gcache.Newstring, string.Build() gc.Set("key", "value") v, err := gc.Get("key") if err != nil { panic(err) } // output: "value" fmt.Println(v) }

Loading Cache

If specified LoaderFunc, values are automatically loaded by the cache, and are stored in the cache until either evicted or manually invalidated.

func main() { gc := gcache.Newstring, string. LRU(). LoaderFunc(func(key string) (string, error) { return "value", nil }). Build() v, _ := gc.Get("key") // output: "value" fmt.Println(v) }

GCache coordinates cache fills such that only one load in one process of an entire replicated set of processes populates the cache, then multiplexes the loaded value to all callers.

Expirable cache

func main() { // LRU cache, size: 10, expiration: after a hour gc := gcache.Newint, int. LRU(). Expiration(time.Hour). Build() for i := 0; i < 3; i++ { gc.Set(i, i*i) } }

Event handlers

Evicted handler

Event handler for evict the entry.

func main() { gc := gcache.Newint, int. EvictedFunc(func(key, value int) { fmt.Println("evicted key:", key) }). Build() for i := 0; i < 3; i++ { gc.Set(i, i*i) } }

Added handler

Event handler for add the entry.

func main() { gc := gcache.Newint, int. AddedFunc(func(key, value int) { fmt.Println("added key:", key) }). Build() for i := 0; i < 3; i++ { gc.Set(i, i*i) } }

added key: 0
added key: 1
added key: 2

Origin Author

Jun Kimura